''CH-7'' or ''No. 7'' (''jp:'' 第七号駆潜艇) was a of the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

History

''CH-7'' was laid down on 30 October 1937 at the

Yokohama is the second-largest city in Japan by population and the most populous municipality of Japan. It is the capital city and the most populous city in Kanagawa Prefecture, with a 2020 population of 3.8 million. It lies on Tokyo Bay, south of To ...

shipyard of Tsurumi Iron Works, launched on 10 June 1938, and completed and commissioned on 15 November 1938. On 8 December 1941, she was assigned to Sub Chaser Division 11 (SCD 11) under Commandeer Hayashi Risaku, 9th Base Force, Southern Expeditionary Fleet. ''CH-8'' and ''CH-9'' were also assigned to the squadron.

Invasion of Borneo

In November 1941, she was assigned to the Borneo Invasion Group (under Rear Admiral Kurita Takeo), code-named " Operation B" ( the invasion of British Borneo). The force consisted of five

Imperial Japanese Army The was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor o ...

transports carrying the 25th Army (''Katori Maru'', ''Hiyoshi Maru'', ''Myoho Maru'', ''Kenkon Maru'', and ''Nichiran Maru''); and five

transports ('' Hokkai Maru'' carrying the No.2 Yokosuka

Special Naval Landing Force The Special Naval Landing Forces (SNLF; ja, 海軍特別陸戦隊, Kaigun Tokubetsu Rikusentai) were naval infantry units of the Imperial Japanese Navy (IJN) and were a part of the IJN Land Forces. They saw extensive service in the Second Sino ...

, ''Tonan Maru No 3'' carrying the 4th Naval Construction Unit, and three transports carrying equipment and supplies, '' Unyo Maru No. 2'', ''Kamikawa Maru'', and ''Mitakesan Maru''). The force was escorted by ''CH-7'' along with and two minesweepers ('' W-3'' and '' W-6'') while two heavy cruisers (, ), two light cruisers ( and ), six destroyers (, , , , , ), provided distant cover; and a seaplane tender () provided air support. On 13 December 1941, the convoy left

Cam Ranh Bay Cam Ranh Bay ( vi, Vịnh Cam Ranh) is a deep-water bay in Vietnam in Khánh Hòa Province. It is located at an inlet of the South China Sea situated on the southeastern coast of Vietnam, between Phan Rang and Nha Trang, approximately 290 kil ...

, Indochina (''Mitakesan Maru'' is later detached to deliver supplies to the Philippines). On 15 December 1941, the transports arrived and disembarked their troops unopposed at

Seria Seria () is a town in Belait District, Brunei, about west from the country's capital Bandar Seri Begawan. The total population was 3,625 in 2016. It was where oil was first struck in Brunei in 1929 and has since become a centre for the countr ...

Miri ) , subdivision_type = Country , subdivision_name = , subdivision_type1 = State , subdivision_name1 = , subdivision_type2 = Division , subdivision_name2 ...

, and

Lutong Lutong is a suburban township in Miri, a city in the state of Sarawak in Malaysia. An oil refinery was built in Lutong by Shell Oil Company Shell USA, Inc. (formerly Shell Oil Company, Inc.) is the United States-based wholly owned subsidiary o ...

, successfully occupying the airfields and oil wells. On 17 December 1941, the destroyer ''Shinonome'' was sunk by a Dutch

Dornier Do 24 The Dornier Do 24 is a 1930s German three-engine flying boat designed by the Dornier Flugzeugwerke for maritime patrol and search and rescue. A total of 279 were built among several factories from 1937 to 1945. Design and development The Dorni ...

flying-boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fusela ...

flying from

Tarakan Tarakan is an island and the largest city of the Indonesian province of North Kalimantan. The island city is located in northern Borneo, midway along the coast of the province. The city boundaries are co-extensive with the island (including a co ...

. CH-7 remained at Miri with one battalion of the 25th Army while the rest of the force departed on 22 December 1941 to occupy

Kuching Kuching (), officially the City of Kuching, is the capital and the most populous city in the States and federal territories of Malaysia, state of Sarawak in Malaysia. It is also the capital of Kuching Division. The city is on the Sarawak River ...

. On 25 December 1941, ''CH-7'' left Miri arriving at

on 26 December 1941.

Invasion of Palembang and Banka Island

On 9 February 1942, she departed

Camranh Bay Cam Ranh Bay ( vi, Vịnh Cam Ranh) is a deep-water bay in Vietnam in Khánh Hòa Province. It is located at an inlet of the South China Sea situated on the southeastern coast of Vietnam, between Phan Rang and Nha Trang, approximately 290 kilo ...

as part of "Operation L" tasked with the invasion and occupation of Palembang and

Banka Island Bangka is an island lying east of Sumatra, Indonesia. It is administered under the province of the Bangka Belitung Islands, being one of its namesakes alongside the smaller island of Belitung across the Gaspar Strait. The 9th largest island in In ...

Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...

. The invasion force consisted of eight transports escorted by subchasers, ''CH-7'' and ''CH-8''; light cruiser ''

Sendai is the capital Cities of Japan, city of Miyagi Prefecture, the largest city in the Tōhoku region. , the city had a population of 1,091,407 in 525,828 households, and is one of Japan's 20 Cities designated by government ordinance of Japan, desig ...

''; destroyers '' Fubuki'', '' Hatsuyuki'', '' Shirayuki'', and '' Asagiri''; and minesweepers ''W-1'', ''W-2'', ''W-3'', ''W-4'' and ''W-5''.

Invasion of Northern Sumatra

On 10 March 1942, she departed Singapore as part of "Operation T" tasked with the invasion and occupation of Northern Sumatra. The invasion force consisted of 4 convoys carrying 22,000 soldiers including the

Imperial Guards Division In Japan, the Imperial Guard is the name for two separate organizations dedicated to the protection of the Emperor of Japan and the Imperial Family, palaces and other imperial properties. The first was the , a quasi-independent elite branch of the ...

. ''CH-7'' served as escort along with section 1 of Minesweeper Division 44 for one of the convoys consisting of the minelayer '' Hatsutaka'', submarine tender ''Nagoya Maru'', and eight transports. The force reached Sumatra unmolested on 12 March 1942 as Allied air and naval power had been severely reduced after the

Battle of the Java Sea The Battle of the Java Sea ( id, Pertempuran Laut Jawa, ja, スラバヤ沖海戦, Surabaya oki kaisen, Surabaya open-sea battle, Javanese : ꦥꦼꦫꦁꦱꦼꦒꦫꦗꦮ, romanized: ''Perang Segara Jawa'') was a decisive naval battle o ...

and the

Dutch East Indies campaign The Dutch East Indies campaign of 1941–1942 was the conquest of the Dutch East Indies (present-day Indonesia) by forces from the Empire of Japan in the early days of the Pacific campaign of World War II. Forces from the Allies attempted u ...

Reinforcement of Burma

On 19 March 1942, she departed

as part of "Operation U" tasked with the reinforcement of Japanese troops in

Burma Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

. The convoy is escorted by subchasers ''CH-7'' and ''CH-8'' along with a light cruiser ''Kashii'' (which serves as flagship), five destroyers (''

Shikinami was the 12th of 24 s, built for the Imperial Japanese Navy following World War I. When introduced into service, these ships were the most powerful destroyers in the world. They served as first-line destroyers through the 1930s, and remained fo ...

'', ''Asakaze'', ''Harukaze'', ''Hatakaze'', and ''Matsukaze''); an escort ship ( ''Shimushu''); a minelayer ( ''Hatsutaka''), 3 minesweepers (''W-1'', ''W-3'', ''W-4''); the 91st Subchaser Division ( AN ''Choko Maru'', PC ''Shonan Maru No. 5'', PC ''Shonan Maru No. 7''); a gunboat (''Eiko Maru''); an

Ōtori-class torpedo boat The were a class of eight fast torpedo boats of the Imperial Japanese Navy built before and operated during World War II. Development To circumvent the terms of the 1930 London Naval Treaty, which limited its total destroyer tonnage the Imperia ...

(''Kari''), and an auxiliary gunboat (''Kosho Maru''). The warships escorted the First Burma Transport Convoy consisting of 32 transports carrying the main body of the

's 56th Division.

Interim

On 14 July 1942, CH-7 is assigned along with ''CH-8'' and ''CH-9'' to Submarine Chaser Division 11, 10th Special Base Force, 1st Southern Expeditionary Fleet, Southwest Area Fleet. She conducts various escort duties throughout southeast Asia primarily in the waters surrounding Vietnam, Indonesia, Singapore, and Malaysia.

Convoy Mashi-03

On 7 November 1944, she departed

Manila Manila ( , ; fil, Maynila, ), officially the City of Manila ( fil, Lungsod ng Maynila, ), is the capital of the Philippines, and its second-most populous city. It is highly urbanized and, as of 2019, was the world's most densely populate ...

for

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

with ''CH-8'' as escort for convoy MASHI-03 consisting of tankers ''Nichinan Maru No. 2'' and ''Shimotsu Maru''. On 8 November 1944, ''Nichinan Maru No. 2'' was torpedoed and sunk by the USS ''Redfin'' (killing 86). On 9 November 1944, ''Shimotsu Maru'' was torpedoed and sunk by the USS ''Barbero'' (killing 39). The convoy was dissolved.

Fate

On 11 April 1945 while conducting escort duty for auxiliary transport ''Agata Maru'' in the

Andaman Sea The Andaman Sea (historically also known as the Burma Sea) is a marginal sea of the northeastern Indian Ocean bounded by the coastlines of Myanmar and Thailand along the Gulf of Martaban and west side of the Malay Peninsula, and separated from ...

11 miles north east of the

Nicobar Islands The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean. They are located in Southeast Asia, northwest of Aceh on Sumatra, and separated from Thailand to the east by the Andaman Sea. Located southeast of the Indian s ...

, she was attacked by

Consolidated B-24 Liberator The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models des ...

bombers of the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...

's No. 203 Squadron. Both ships were sunk at . ''CH-7 '' was removed from the

Navy list A Navy Directory, formerly the Navy List or Naval Register is an official list of naval officers, their ranks and seniority, the ships which they command or to which they are appointed, etc., that is published by the government or naval autho ...

on 25 May 1945.